Over the past century, realism and liberalism have been the two warring imperatives behind most U.S. foreign policies. According to these two stimulating new books, the United States and its policymakers have seldom managed to reconcile these two approaches or match ideologically driven liberal projects with the realities of power, interest, and expense.

The United States is struggling with just such a problem at the moment. The administration of George W. Bush, like some of its predecessors, claims to be both realistic and true to American ideals. In 2002, Condoleezza Rice, when she was still national security adviser, asserted that the administration's emphasis on both preventive war and democracy promotion (articulated in its 2002 National Security Strategy) transcended what she called the false academic dichotomy between realism and idealism. "In real life," she declared, "power and values are married completely." And Bush has denigrated skeptics "who call themselves 'realists'" but "have lost contact with a fundamental reality" -- that "America is always more secure when freedom is on the march."

Events, however, do not seem to be cooperating. Washington is currently mired in a costly war that is part of a dubious strategy of democratic regime change. And a fierce fight has broken out within the neoconservative brain trust: Francis Fukuyama has denounced Charles Krauthammer's strategy of "democratic realism" (which advocates the use of military force and elections to transform the Middle East), arguing that it is neither democratic nor realistic.

Both Christopher Layne, of Texas A&M, and Colin Dueck, of the University of Colorado, point out that such tensions are nothing new; indeed, the United States' liberal ambitions have, since the era of Woodrow Wilson, repeatedly clashed with the realities of power politics. Layne and Dueck converge in some of their analyses, but they diverge in their prescriptions. For example, Layne proposes to resolve the conflict between liberalism and realism through a strategy of engagement so limited that it borders on isolationism. Dueck, by contrast, seeks a prudent balance between modest liberal ambitions and politically sustainable commitments. In the end, both are too pessimistic about Washington's ability to shake off its ideological impulses and find the right balance. A prudent realism is not only compatible with the achievement of liberal U.S. aspirations in world politics; it is a precondition for success.

THE PERILS OF PRIMACY

Layne and Dueck are not mere pundits reacting to depressing headlines, but political scientists who have spent serious time in the archives and ground their criticisms in coherently articulated philosophical positions. Layne, who has warned readers for years about the dangers of American hubris in a unipolar world, has earned the right to say, "I told you so."

Like many eclectic younger scholars of international relations, Layne and Dueck call themselves "neoclassical realists." This means that they anchor their analyses in questions of the relative power of states and their national interests but allow for the role of other factors, such as ideology and domestic politics. International politics, in this view, is not inexorably condemned to be a Hobbesian tragedy -- but it can turn into one if states are misguided by their illusions.

The United States' physical distance from Eurasia has sometimes tempted it to remain aloof from what happens there. Yet the country has enjoyed such preponderant power that it has also been tempted to impose abroad what Layne calls "Open Door hegemony" -- demanding that countries open their economies, conform to U.S. ideas and institutions, and unquestioningly accept U.S. leadership. Although this situation might seem advantageous, it is (as both authors point out) actually dangerous. Layne shows how Washington's ideologically motivated assertions of hegemony repeatedly provoke fear and resistance abroad, embroiling the United States in costly and counterproductive contests with other countries. Dueck, meanwhile, worries that U.S. policymakers too often try to pursue their liberal goals on the cheap, in ways that risk failure and bring on rash attempts to stave off humiliating defeats.

The two books offer overlapping accounts of U.S. grand strategy since the presidency of Woodrow Wilson but trace distinct historical plot lines. Layne focuses on the way that the country has repeatedly squandered its luxuries of power and insularity to pursue the goal of liberal dominance in Eurasia. During World War II, Layne writes, the country aimed to "throttle Germany and Japan" and "knock Britain from its great power perch." When the war was over, the "political collapse of Europe" gave Washington the chance to consolidate its hegemony.

In Layne's telling, confronting the war-weakened Soviet Union was almost an afterthought. Stalin, he claims, actually wanted to pursue détente with the United States and was only dissuaded when the Marshall Plan revealed U.S. intentions to force open Eastern Europe and achieve hegemony on the continent. Layne unconvincingly asserts that Harry Truman could have struck a deal with Stalin to set up Germany as an independent state, thereby reestablishing a balance of power in Eurasia and allowing the United States to withdraw across the Atlantic. But Washington rejected that option; with its "huge superiority in power, it did not need to be overly concerned about how Moscow would respond to American policy." Instead, as Layne quotes the diplomatic historian Melvin Leffler, "American leaders -- moved by a traditional missionary impulse, convinced by their global responsibility, full of the self-confidence that comes of success, fundamentally unhurt by war in a wounded world -- eagerly reached for the mandate of heaven."

Layne sees the subsequent Cold War in Europe as having been more about maintaining U.S. economic access and keeping the United States' NATO allies down than it was about keeping the Soviets out. And after the Soviet Union collapsed, the United States continued its quest for hegemony -- proof, according to Layne, that Washington had always had ambitions beyond just keeping Moscow from dominating Eurasia. These ambitions, Layne writes, are what explains the United States' present predicament as well. "Fundamentally, 9/11 was about geopolitics," he declares, "specifically about U.S. hegemony. ... It is American policies -- to be precise, American hegemony -- that make the United States a lightning rod for Muslim anger."

Given the costs, why has the United States worked so hard at maintaining an "open door" around the world? Layne points to a confluence of ideological fears and economic interests. Without presenting much evidence, he asserts that "the United States has pursued hegemony because that grand strategy has served the interests of the dominant elites that have formed the core of the U.S. foreign policy establishment since at least the late 1930s."

His account, however, is far too one-sided to convince, and Layne is wrong on many key issues. In his historical overview, he ignores the fact that the U.S. decision to withdraw from active participation in balancing power in Eurasia in the 1930s was a disaster, and that the U.S. victory in the Cold War came cheap compared to other historic contests for hegemony. Moreover, Stalin would never have accepted a deal to set up a truly independent Germany, because he rightly feared a rerun of World War II. And NATO was created because the Europeans pushed for it; if anyone was ambivalent about it, it was the U.S. Congress, which was reluctant to fund ongoing troop deployments abroad. More generally, Layne is right to worry that U.S. dominance may provoke resistance. But he overlooks the critical fact that during the Cold War, most states balanced against the weaker but more threatening Soviet Union, rather than against the stronger but more attractive United States. The result of such skewed historical judgments is that Layne unfairly dismisses the possibility that a consensual international order based on prudent, liberal American leadership could emerge.

LIBERALS ON THE CHEAP

Dueck's account is more differentiated and better explains the United States' current impasse. He argues that U.S. grand strategy has typically been marked by an ideological commitment to remake the world in the United States's own liberal self-image -- and by a countervailing urge to do it on the cheap. This cheapness, and the habit of what he calls "limiting liability," comes, according to Dueck, from tradition ("no foreign entanglements"), geography (the oceans make it feasible), and institutions (the brake exercised by Congress) -- all of which he lumps together as "culture." Dueck finds examples of this pattern throughout U.S. history: in Wilson's inability to secure U.S. membership in the League of Nations; in Truman's attempt, pre-1950, to contain the Soviet Union with inadequate military forces; in Bill Clinton's Bosnia policy; and in Bush's invasion of Iraq with a small army and no plan for the occupation.

Unlike Layne, Dueck not only expounds his main theme but also explains variations on it. He classifies strategic schools by their degree and type of liberalism and by the extent of their concern with limiting liability. Thus, for example, he considers Progressives (such as Henry Wallace and George McGovern) to be liberal idealists who seek to limit U.S. commitments abroad. Internationalists (Wilson, Franklin Roosevelt, Truman, and John F. Kennedy) are liberals who expand U.S. commitments. Nationalists (Robert Taft and Jesse Helms) seek to limit liability and the relevance of liberal ideas in foreign affairs. And realists (Richard Nixon and Henry Cabot Lodge) also set aside liberal ideals in foreign affairs but are more willing to use force to compete for dominance abroad. According to Dueck, which school prevails at a given moment depends in part on the international situation: rising threats diminish the instinct to limit liability. In practice, this means that rising threats normally play into the hands of liberal internationalists, because realism does not resonate with the United States' liberal political culture.

Although he notes these general patterns, Dueck is not a determinist. He argues that the outcomes of struggles over grand strategy ultimately depend on electoral politics and how presidents shape options and build coalitions. He shows, for example, how Wilson's ideological framing of the peace issue and Republican political tactics in 1919 removed from consideration the perfectly plausible options of a more limited League of Nations or a postwar alliance with the United Kingdom and France, even though the realist Republican establishment favored such options.

For Dueck, Bush's grand strategy after September 11 "was the result of a pattern of strategic adjustment that has occurred repeatedly and predictably in American history: international shocks and pressures created an opening for new strategic ideas, and leading state officials took the opportunity to put forward their preferred approach, based largely on their culturally influenced perceptions of the national interest." In other words, "as [Secretary of Defense Donald] Rumsfeld put it, September 11 offered 'the kind of opportunities that World War II offered, to refashion the world.'" Bush explained in February 2003 that "a liberated Iraq can show the power of freedom to transform that vital region." But Bush pursued these "extremely ambitious and idealistic foreign policy goals without initially providing the full or proportionate means to achieve those goals," says Dueck, which made Bush "very much a Wilsonian."

Dueck underrates the continuity between the pre-9/11 realist phase of the Bush administration, with its inclination toward tough bargaining and its skepticism about nation building, and its later turn to preventive war and belligerent rhetoric about democracy promotion. For key figures such as Vice President Dick Cheney and Rumsfeld, the democracy subtheme in "the war against terror" was mainly window-dressing for a policy of security through the use of force.

Even so, the rhetoric mattered. Like Wilson, Bush used his agenda-setting powers to limit and polarize the available policy choices on Iraq. He removed from consideration moderate options favored by many experts, such as applying steady pressure on Iraq or pursuing limited aims. Thanks to the crisis atmosphere after September 11 and the grandiosity of ambition underwritten by unipolarity, Bush's call to wage a war on "evil" initially gained the backing of over 80 percent of Republicans, Democrats, and independents.

Dueck argues that grand strategies generally persist until they have been proved a failure and are overturned in an election. Would that it were so. In fact, support for the Vietnam War, for example, declined steadily from 1966 to 1971 among Democrats, Republicans, and independents, and the party that started the war was thrown out of the White House in 1968. Yet Washington continued the war until 1973, albeit after adjusting troop deployments to reduce casualty levels.

Today there is a new, more polarized pattern. In the 1980s and 1990s, even as Republicans and Democrats moved further apart on domestic issues, the differences between them on foreign policy remained comparatively minor, and partisan opinions on both sides changed in response to events. Bush's reframing of U.S. foreign policy since September 11 has changed that pattern. Republican support for the Iraq war has eroded only modestly in the last three years, even as support from Democrats and independents has taken a nosedive. This pattern of polarization extends to issues unrelated to the war: in 1998, for example, polls indicated that 31 percent of Republicans believed that the globe was warming, but by 2004 they showed that only 26 percent did (even as the numbers increased among Democrats and independents).

What does all this portend for the Bush variant of Wilsonian internationalism? The answer is not clear. Failure plus an election usually means change, Dueck argues. But he also stresses presidents' ability to use foreign threats to set the strategic agenda to suit their purposes. Although there is no precedent for anyone managing this trick after a failed war, the persistence of Republican support for Bush's strategy of preventive war, combined with widespread nervousness over Iran's nuclear program, could breathe a second wind into the administration's sails.

DELIMITING LIBERALISM

If Bush's grand strategy of regional transformation in the Middle East does collapse, will it be replaced by something better? Layne argues for "offshore balancing," which relies on a regional balance of power emerging spontaneously among Iran, Saudi Arabia, and Iraq, as the United States uses its air force and navy to oversee things from afar. But Layne does not hold out much hope that this strategy will be adopted. Dueck's prescription -- to scale down liberal aims so that they can be matched with sustainable policy -- is less of a departure from the pre-Bush norm, but he, too, is skeptical that Washington will ever find the right balance.

A closer look at Dueck's theory, however, suggests that his pessimism may be unwarranted even in his own terms. Moderate liberal internationalism -- a blend of realist prudence with measured, steady support for international institutions and democracy abroad -- is perfectly compatible with American strategic culture as he describes it. (In fact, it is what even some former neoconservatives, such as Fukuyama, now recommend.) Dueck himself suggests that the best U.S. policy in 1919 would have been to join the League of Nations but without accepting an unconditional commitment to fight any aggressor, while simultaneously forming an alliance with the other two great liberal democratic powers, France and the United Kingdom. This pragmatic yet liberal option was shunned, Dueck writes, not because it was inherently unacceptable to U.S. culture but because of Wilson's arbitrary, polarizing way of framing the issue. Bush made a similar mistake. Using multilateral pressure to neutralize the threat from Saddam Hussein was not unworkable strategically or culturally; the option was simply pushed aside by the White House in favor of nearly unilateral preventive war.

In fact, a key reason why the United States won the Cold War at a reasonable price (apart from its unfortunate detour into Vietnam) was its cost-conscious, moderately liberal, realism-informed grand strategy. Washington relied on the country's tremendous military and economic power, the attractiveness of its society and political institutions, and its strategic restraint to attract allies and institutionalize cooperation among them. Postwar U.S. leaders resisted reckless calls to roll back the Red Army in Eastern Europe or to launch a preventive war against the rising Soviet military threat. U.S. forces were generally welcomed when they acted as liberators, not marauders. In 1956, the United States stood on the right side of history at Suez when it slammed the door on colonialism. It put its power at the service of international institutions that have helped to reconcile open world markets with economic and political stability. It presided over an international system where many more states have become democratic. Most countries sided with the United States because its liberal world system worked -- and worked for them.

Even the U.S. instinct for limited liability is, on balance, an asset. The cost-consciousness of voters (who pay the price of reckless policies) echoes classical realists' call for prudence. Democracies are smarter than autocracies when it comes to picking the wars they choose to start; they win over 90 percent of them, and with fewer casualties. This is not simply because democracies are stronger, but also because their voters care about costs, have access to information and expert analysis, and can hold their leaders accountable for mistakes. Democratic empires sometimes blunder into overextension, but in comparison to autocratic ones, they are much quicker to retrench after failures. When the German and Japanese empires got overextended, they tried to solve the problem by attacking on an even wider scale; when the British and the Americans blundered into quagmires in the Boer War and the Vietnam War, respectively, they cut their losses.

Dueck is right, however, that the United States has not always struck a perfect balance between its liberal ambitions and the resources needed to realize them. One recurrent problem is that the United States sometimes makes hollow promises to protect a vulnerable minority -- such as the Bosnian Muslims of Srebrenica, the Kosovar Albanians, the Rwandan Tutsi, or the people of Darfur. This sometimes goads tyrannical majorities into accelerating ethnic cleansing so as to prevent a troublesome minority from linking up with its supporters in the West. Even when U.S. promises to vulnerable groups are not hollow, the aid sometimes arrives too late. The problem is not just the American instinct to limit liability, but Washington's tendency to conduct overly ambitious diplomacy, such as when the White House took an uncompromising position against Serbia at the Rambouillet talks. The humanitarian impulse is not wrong, but it needs to be administered with a strong dose of realism.

The second recurrent problem that results from U.S. political culture is the temptation to embark on ideological crusades. This temptation is not in fact inherent to liberal internationalism; it is a perversion of it. Dueck's historical analysis shows that the main danger in the U.S. system is that it allows an ideologically polarizing leader to capitalize on external threats -- whether real or imagined -- to frame questions of grand strategy in terms of a liberal crusade. Fortunately, although U.S. political culture makes this outcome possible, it also provides the means necessary to expose such visions as strategically unsound and, in fact, illiberal. The solution is not to give up on the liberal strategic culture that has generally served the United States and the world well. It is, rather, to remain vigilant against attempts to exploit fear in order to hijack U.S. foreign policy in the service of a strategy that is neither liberal nor realistic.